[en] Recently the superfluidity in 2-dimensional helium film was actively investigated theoretically and experimentally. By measuring the third-sound damping associated with the amplitude of the oscillation and/or with the externally driven rotation, the vortex dynamics in 2-dimensional superfluid films of helium-4 was systematically investigated. Firstly, the effective vortex density, when there are present pair breakings of bound pairs, was measured for both situations when the net vorticity of the system is zero and non-zero. The measured effective vortex density for the former case was compared with the theoretical predictions and that for the latter case was used to determine an empirical relation between the effective density of rotation-induced vortices and of the vortices from pair breaking. Secondly, the effective diffusion constant was measured and fitted experimentally. Thirdly, the decay of persistent current was measured in an open geometry when vortices leave the film and enter the film. Fourthly, a new measure of persistent current discovered is described

[en] A study of light scattering from random rough characterised rough surfaces is presented. The surfaces considered were in most cases metallic single scale surfaces having a surface height of known first order probability density function and known autocorrelation function. The first part of the thesis is concerned with the actual manufacture of these characterised rough surfaces, and the description of the equipment used to measure the scattered light from the rough surfaces i.e. the scatterometer. Then the physical optics scattering theory is developed for surfaces whose surface structure is on the order or larger than the incident wavelength by using the physical optics approximation; different probability density functions for the surface height are considered and the effect of this difference on the scattered light is studied. It is shown that the physical optics theory agrees well with the experimental data, but only when certain conditions hold, such as low mean slope and small angle of incidence. The validity of the physical optics solution is discussed. Then, scattering of light from high sloped surfaces is discussed. In measuring the scattered light from such surfaces, interesting effects are noted; the presence of a large cross polarised component, and the enhanced backscatter peak. Both of these effects can be qualitatively explained by a simple model using multiply reflecting rays. An analysis of the Stokes' parameters of the scattered light supports this simple model. The study of scattering of light from one dimensional surfaces is presented. The numerical code for the exact calculation of the scattered light from one dimensional rough surfaces (finite conductor) i.e. random gratings is developed, and the calculated values are compared with experimental data obtained using a surface that is a good approximate to a one dimensional gaussian random surface. (author)

[en] An underground coal mine roadway dewatering network is a highly variable, constantly changing system. Pumps used in this environment need to achieve a wide range of duties that may change regularly. This article discusses the use of and preferred methods in the context of an Australian underground coal mine with conditions particular to this industry.

[en] In this study, a numerical method for Soil-Structure Interaction (SSI) analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution and coupled with near field modeled by finite elements. In order to verify the seismic response analysis, the results are compared with those of other commercial code. Finally, several SSI analyses which induced seismic loading are performed to examine the dynamic behavior of the system. As a result, it is shown that the developed method can be an efficient numerical method for solving the SSI analysis

[en] A fuel failure detection system (FFDS) by monitoring gamma rays at primary cooling pipes had been installed and used in HANARO. It has been confirmed, from 6 years of operating experience that N-16, a dominant high energy gamma radiation of primary coolant adversely affect an efficient detection of fuel failure. As an alternative for solving the current points in issue and ensuring effective fuel failure detection, a delayed neutron measurement concept was suggested. Having been proved by the field application test to do be much more sensitive than the previous system in fuel failure detection, the new FFDS will improve the reactor safety

[en] The performance tests for shielding of BNCT irradiation room and beam monitoring system are carried out. The neutron and gamma dose rates of the inside and outside of irradiation room are measured, and the radiation levels are found to be permissible for BNCT experiment, but the interference with other experimental facility is observed. So, the shielding of the irradiation room is complemented. In order to monitor the neutron and gamma-ray around the beam port, detection systems with fission chamber and ion chamber are constructed, and their performance tests are carried out. The count rate of fission chamber and the current of ion chamber are fairly proportional to the reactor power. Also, it is confirmed that the continuous monitoring of the reactor power and shutter operation while the patient is under irradiation for BNCT can be made

[en] The use of ionizing radiation in food processing has received increased interest as a means of reducing the level of foodborne pathogens. This overview discusses the regulatory issues connected with the use of this technology in the United States. Several recent changes in the FDA's review process are discussed. These include the current policy that utilizes an expedited review process for petitions seeking approval of additives and technologies intended to reduce pathogen levels in food, and the recent USDA rule that eliminates the need for a separate rulemaking process by USDA for irradiation of meat and poultry. Recently promulgated rules and pending petitions before the FDA associated with the use of ionizing radiation for the treatment of foods are also discussed along with the current FDA labeling requirements for irradiated foods and the 1999 advanced notice of proposed rule on labeling. Another issue that is presented is the current status of the approval of packaging materials intended for food contact during irradiation treatment of foods

[en] At the Z^o or a B factory, there are two tests for non-CKM-type leptonic CP violation in the τ → ρν(a₁^-ν) decay channel by inclusion of ρ(a₁) polarimetry. By CP invariance, the moduli ratio of, and the phase difference between, the two helicity amplitudes for τ^- → ρ^-ν(a₁^-ν) decay should equal those for τ⁺ → ρ⁺anti ν(a₁⁺anti ν) decay. Formulas are given for a L-handed ν_τ, and also for an arbitrary mixture of ν_L and ν_R neutrino helicities. Statistical errors are listed for both the case that the τ ^- momentum direction is not know, and when it is known via a silicon vertex detector

[en] Among many parameters needed to characterize subsurface rock mass related to underground storage and disposal projects, an important one is the heat production rate of the bedrock itself. The rock produces heat from the decay of radioactive isotopes consisting of minerals and its gamma-ray emissions, of which the magnitude is dominated by contents of major radioactive isotopes, e.g., uranium, thorium, and potassium. The heat production rate is generally calculated from the rock density and the radiogenic isotope contents, which can be measured from the spectrometry of drilled cores or rock fragments. However, such approaches are rarely available in deep boreholes because recovering rock samples from several hundred meters to a few kilometers is quite difficult. A recent geophysical logging technique for deep boreholes is available where the uranium, thorium, and potassium contents are measured from the gamma-ray spectrum. However, this technique requires the density to be measured separately, and the measurement depth of the equipment is still limited. As an alternative method, a natural gamma-ray logging tool was adopted to estimate briefly the heat production from the total gamma activity, which is relatively easy to measure. This study introduces the development of the proposed method for evaluating the heat production of a granitic rock mass with domestic commercial borehole logging tools, as well as its application and verifications in deep boreholes.

[en] Most of the arsenic detected was arsenite [As(III)]. - Groundwater samples, taken from 73 wells in 10 counties of southeast Michigan in 1997 had arsenic concentrations in the range of 0.5 to 278 μg/l, the average being 29 μg/l. About 12% of these wells had arsenic concentrations that exceeded the current USEPA's maximum contaminant level of 50 μg/l. Most (53-98%) of the arsenic detected was arsenite [As(III)] and other observations supported the arsenic species distribution (low redox potential and DO). In shallow groundwater (<15 m), arsenic concentrations are low likely due to the formation of insoluble ferrosoferric hydroxide complex. In deep groundwater (>15 m), the concentration of arsenic is possibly controlled by reductive dissolution of arsenic-rich iron hydroxide/oxyhydroxide and dissolution of arsenic sulfide minerals